1. Field of the Invention
The present invention relates to network communication, and, more particularly, to a packet processing node for network communication.
2. Description of the Related Art
In many communication systems, any transmission from one node is sent to a plurality of connected nodes. In such broadcast systems, the information may only be relevant to a single receiver, but all nodes must process the transmission to determine its intent. Data on such networks are usually broken into pieces known as packets. A packet is formed of consecutive bytes that may be marked by leading and/or trailing delimiters. Protocols by which nodes communicate usually divide a packet into the protocol-relevant information (the header) and the data relevant to the receiving node (payload).
It is known for the protocols to be “layered” so that the payload area of a lower protocol contains a packet of the next higher layer protocol. Most communication environments require that addressing information be contained at fixed locations (in the first few bytes) of the lowest layer protocol header so that hardware can help discard unwanted packets by simple filtering.
There are many examples of commercially available network devices that perform such filtering. Practically all Ethernet media access controllers (MAC's), for instance, provide for filtering based on an exact match of the first six bytes of a packet header to a programmed value (the network address). This greatly reduces the load of the general-purpose central processing unit (CPU). However, many network frames that are addressed to the node either distinctly or by a shared address are still not relevant to a particular node. The receiving equipment may be required to look at an entire packet to determine its relevance. Additional cost is inherent in networked systems because memory is required to store the entire packet while the processing elements perform the analysis.
Most of the existing patents relating to packet filtering are a result of the very competitive commercial network switch and router market. Routers must sort received frames into subsets based on different byte fields within a packet. To achieve high throughput, specialized hardware can be used to perform this sorting. In all known cases, an assumption is made that a CPU is present and only assists the microprocessor in performing its task. A problem is that a microprocessor adds significant cost to the product.
What is needed in the art is a device for network communication that does not require a microprocessor.